High current busbar system for low-profile power shelves

ABSTRACT

A low profile (1U) power distribution system includes a power shelf assembly having a first side and an opposing second side. First and second bus bars extend across the assembly and substantially in parallel with the first and second sides, the second bar positioned behind the first bar. One row of power supply pins extends from the bars to engage power supply units within the assembly. A first set of pins extends from the first bus, while a second set extends from the second bar and protruding through respective apertures in the first bar. An insulating material may be provided to electrically insulate power supply pins of the second bar from the first bar. The reduced height profile of the bars allows for cooling air to pass through the remaining &gt;50% of the assembly, which may now desirably include additional electrical circuits within the cooling channel.

A portion of the invention of this patent document contains materialthat is subject to copyright protection. The copyright owner has noobjection to the reproduction of the patent document or the patentinvention, as it appears in the U.S. Patent and Trademark Office patentfile or records, but otherwise reserves all copyright rights whatsoever.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationNo. 62/101,430, dated Jan. 9, 2015, and which is hereby incorporated byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO SEQUENCE LISTING OR COMPUTER PROGRAM LISTING APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of powerdistribution systems. More particularly, the present invention relatesto low-profile power shelves incorporating one or more switch mode powersupplies providing a relatively low DC output voltage (e.g. 12V) at veryhigh current (e.g. 1500 A) to power servers, storage or networkingequipment.

With ever-increasing power consumption demands in server equipment, forexample, increasing or at least more reliable airflow rates are neededto effectively cool such high power distribution systems. The associatedelectrical components are typically cooled by air moving in parallelairflow channels, through convection or otherwise forced-air mechanisms(e.g., fans or blowers).

However, particularly with respect to certain low-profile configurations(e.g., single “1U” rack units) the airflow channels are often restrictedin size, thereby stressing the cooling abilities of the system. This maybe even further exacerbated by the typical presence of electricalcomponents, data cables and power cables which are disposed alongsidethe necessary bus bars. Still further, conventional cooling tools suchas heat sinks with dedicated forced-air mechanisms typically require aheight profile which is incompatible with for example a 1U power shelf.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, an arrangement of bus bars is provided in a low profilepower shelf where the buses are arranged one behind each other. Theelectrical connection of the rear bus bar is established by asubstantially round pin protruding from the front bus bar and beingisolated from the front bus bar. The bus bar arrangement uses less than50% of the total shelf height.

An exemplary embodiment of a bus bar system involves the usage of twosubstantially rectangular copper or aluminum bus bars of the same sizeand arranged one behind the other in the shelf. The bus bars occupy onlya first portion of the low profile shelf height (typically 50%), leavingthe rest open so that the remaining shelf height can be used for otherelectrical connections and, significantly, allowing cooling air to passfrom or to power supplies disposed within the power shelf assembly. Thisair will at the same time also cool the first and second (i.e., positiveand negative connection) bus bars.

The electrical connection from the bus bars to the power supplies may beestablished by substantially round pins, wherein the single or multiplepin(s) connecting the rear bus bar to associated power supply outputsare protruding through corresponding apertures in the front bus bar. Thepins can have an additional isolating material around them to avoidelectrical short circuits. The front bus bar is connected throughsimilar pins directly to associated power supply outputs.

This arrangement allows arrangement of the bus bars one behind the otherinstead of having them one on top of the other.

The proposed arrangement further preferably leaves enough space in thecross section of the shelf for additional low profile components and forair passing through the shelf to cool the power supply units and at thesame time also the bus bars.

A power distribution system implementing such an arrangement mayinclude, e.g., six power supplies each providing 3 kW of power at anoutput voltage of, e.g., 12V. This results in a total output current of6×250 A=1500 A. The overall height of the low profile shelf is one rackunit (i.e., 1U or ˜40 mm). A copper bus bar conducting 1500 A of currentwithout generating excessive losses should not be loaded with more than˜3 A per mm² cross section. This results in a required bus bar crosssection of at least 500 mm². With the proposed arrangement, a bus bar of20×25 mm can be selected, at least theoretically leaving >50% of theshelf cross section for other electrical connections and the air flowthrough the shelf.

The arrangements of bus bars one behind the other allows to reducesignificantly the height occupied by such bar bars and allows forincreased power outputs in low profile 1U shelves.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is an exterior perspective view representing an embodiment of apower shelf assembly with an exemplary bus bar configuration accordingto aspects of the present invention.

FIG. 1B is a perspective view representing an interior of the embodimentof the power shelf assembly of FIG. 1A.

FIG. 2 is a reverse perspective view of the power shelf assembly in FIG.1B.

FIG. 3 is a perspective view of an embodiment of the bus barconfiguration from the power shelf assembly in FIG. 1B.

FIG. 4 is an enhanced perspective view of the embodiment of the bus barconfiguration in FIG. 3.

FIG. 5A is an overhead view of the embodiment of the bus barconfiguration in FIG. 3.

FIG. 5B is a front view of the embodiment of the bus bar configurationin FIG. 3.

FIG. 5C is a cross-sectional overhead view of the embodiment of the busbar configuration in FIG. 3.

FIG. 6 is a diagram representing an embodiment of a power shelf assemblyof the present invention, having an exemplary bus bar configurationinteracting with a power supply disposed therein.

FIG. 7 is a diagram representing an embodiment of a power shelf assemblyof the present invention, having an exemplary bus bar configuration andprinted circuit board interacting with a power supply disposed therein.

DETAILED DESCRIPTION OF THE INVENTION

Referring generally to FIGS. 1A-7, various exemplary embodiments of aninvention may now be described in detail. Where the various figures maydescribe embodiments sharing various common elements and features withother embodiments, similar elements and features are given the samereference numerals and redundant description thereof may be omittedbelow.

An exemplary embodiment as disclosed herein and further with referencegenerally to FIGS. 1A-7 relates to high power density power shelves, asused for example in server systems to convert AC power to the requiredDC power at low voltage, high current of the servers. To reach highpower densities, low profile 1U (˜40 mm) shelves are used in conjunctionwith high power density switching power supplies. The increased powerrequirements of server systems further require heavy copper bus bars tocarry supply currents in the excess of 1500 A from such shelves.

An exemplary bus bar configuration as disclosed herein allows the outputcurrents from each power supply unit in a low profile shelf assembly tobe collected in such a way that minimal height in the shelf is used forthe overall bus bar system, leaving enough space for other connectionsand, more importantly, leaving enough space for air to cool the powersupply units in the shelf.

Referring first to FIG. 1A. 1B and 2, an exemplary embodiment of a powershelf assembly 10 includes a housing defining a low profile interiorhaving a height of, e.g., 1U (corresponding to the standard height ofone shelf in a power supply rack, about 44.5 mm). The assembly mayfurther define one or more channels 16 to receive a like number of powersupply units on a first end of the housing, and further is configured toreceive a bus bar arrangement 20 on a second end.

As illustrated herein, the housing may be referred to as having a leftside 11, a right side 12, a bottom 13 and a top defined by a lid 14, butthe associated perspective view is for illustrative purposes only and isnot intended as limiting an arrangement or orientation of the assembly10. While a power shelf assembly 10 is generally described herein in thecontext of having an interior defined by an enclosure on all but oneside, a power shelf assembly may within the scope of the presentinvention further encompass a power shelf of a single rack unit amongmany in, for example, a server rack having a stacked plurality of rackunits, and without specific reference to a floor, lid or sides definingor otherwise requiring an enclosed interior. Indeed, an exemplary powershelf assembly 10 may within the scope of the present invention begenerally defined with respect to a spatial configuration andorientation of a bus bar arrangement 20 as further disclosed herein,relative to one or more power supply units which may be received andcoupled thereto. One of skill in the art may appreciate that the term“shelf” as used herein may include any element or combination ofelements supporting required objects or components as disclosed herein,and may be shaped to be not only rectangular but potentially square, oreven having curved contours at one or more edges.

The housing further may be configured with a number of external signalconnections 18 (FIG. 2) disposed on a rear side of the assembly, orotherwise opposing the side configured to receive the power supplyunits.

Referring to FIG. 3, an embodiment of a bus bar arrangement 20 asdisclosed herein is configured so as to occupy only a first (e.g.,upper) portion of the respective end of the power shelf assembly 10. Afirst bus bar 22 may extend substantially across the power shelfassembly and in parallel with the bottom 13 and top 14 of the assembly10. A second bus bar 24 also extends along the same plane and may bemounted directly behind the first bus bar 22, wherein a substantiallyidentical height profile of the low profile shelf assembly is occupiedby the bus bars.

In an embodiment, the bus bars 22, 24 may be substantially rectangularcopper or aluminum bus bars of the same size, collectively occupying 50%or less of the available height (i.e., as defined between the bottom andtop of the interior).

A first set of bus bar pins 28 is coupled to the first bus bar 22 andextends in parallel with the bottom and top planes of the assemblytoward the channels 16 for direct coupling with any associated powersupply units. A second set of bus bar pins 26 is coupled to the secondbus bar 24 and extends in parallel with the first set of pins 28,wherein a single row of pins 26, 28 extends for electrical coupling withthe power supply units.

The first set of pins may collectively differ in length from the secondset of pins, either based on structural requirements for the powersupply units to be implemented, or to implement a specific contactsequence when a power supply is plugged in or out or otherwise simply tofacilitate visual distinction between the respective pins bytechnicians. In various embodiments, however, the various pins may havesubstantially identical cross-sectional shapes and sizes.

One or more coupling devices may further be provided for coupling eachbus bar 22, 24 to the assembly 10 and/or external connections thereto,including for example but not limited to respective brackets, fasteners,hinges, rails and the like.

Referring now to FIGS. 4, 5A, 5B and 5C, in one embodiment the secondset of pins 26 extends from the second bus bar 24 through correspondingapertures 30 in the first bus bar 22 and accordingly protrudes the firstbus bar 22 and toward the power supply units. In an embodiment, aninsulating material 32 is provided about at least the second set of pins26 with respect to at least the corresponding apertures in the first busbar 22, wherein electrical short circuits may be avoided.

In a particular example, and by further reference to FIG. 6, theassembly 10 as described may include, e.g., six power supply units 36each providing 3 kW of power at an output voltage of, e.g., 12V. Thisresults in a total output current of 6×250 A=1500 A. The overall heightof the low profile shelf 10, as previously noted, is one rack unit(i.e., 1U or ˜40 mm). A copper bus bar 22, 24 conducting 1500 A ofcurrent without generating excessive losses should not be loaded withmore than ˜3 A per mm² cross section. This results in a required bus barcross section of at least 500 mm². With the proposed arrangement, a busbar of 20×25 mm can be selected, at least theoretically leaving theaforementioned >50% of the shelf cross section for air flow 40 throughthe shelf, as may for example be generated or otherwise facilitated byconvection cooling or forced-air cooling.

In various embodiments a cooling mechanism may be provided in the formof, for example, cooling fans 38 associated with power supply units 36themselves, which may be oriented to regulate air flow in any of one ormore directions. In other embodiments, cooling may be facilitated fromoutside of the assembly and further via the air channel proximate thebus bars, as well as air intakes and exhaust portions associated withthe assembly housing and the power supply unit.

In another example, and by reference to FIG. 7, the space between thebus bar configuration 20 and the floor 13 of the assembly 10 may furtherbe implemented for the placement of additional circuit boards 42 orother electrical components. This circuitry 42 may provide, for example,interconnects between external connectors 18 on the shelf 10 and thevarious power supply units 36, for electrical signals or even the AC (orDC) input power to the power supply units. The cooling air flow 40 mayin this example further provide cooling to electrical intermediaryconnections or other electrical components as may be desirably providedon the printed circuit board 42.

Throughout the specification and claims, the following terms take atleast the meanings explicitly associated herein, unless the contextdictates otherwise. The meanings identified below do not necessarilylimit the terms, but merely provide illustrative examples for the terms.The meaning of “a,” “an,” and “the” may include plural references, andthe meaning of “in” may include “in” and “on.” The phrase “in oneembodiment,” as used herein does not necessarily refer to the sameembodiment, although it may.

The term “coupled” means at least either a direct electrical connectionbetween the connected items or an indirect connection through one ormore passive or active intermediary devices.

Conditional language used herein, such as, among others, “can,” “might,”“may,” “e.g.,” and the like, unless specifically stated otherwise, orotherwise understood within the context as used, is generally intendedto convey that certain embodiments include, while other embodiments donot include, certain features, elements and/or states.

The previous detailed description has been provided for the purposes ofillustration and description. Thus, although there have been describedparticular embodiments of a new and useful invention, it is not intendedthat such references be construed as limitations upon the scope of thisinvention except as set forth in the following claims.

What is claimed is:
 1. A power distribution system comprising: a powershelf assembly having a first side, an opposing second side, and adefined interior between the first and second sides, and wherein aheight of the assembly comprises one rack unit (1U); a first bus barextending in parallel with planes corresponding to the first side andthe second side of the assembly; a second bus bar extending in parallelwith the first bar and disposed between the first bus bar and the firstside of the assembly; a first set of one or more power supply pinsextending from the first bus bar toward the second side of the assemblyand perpendicular with respect to the first bus bar; and a second set ofone or more power supply pins extending from the second bus bar towardthe second side of the assembly and perpendicular with respect to thesecond bus bar, the second set of power supply pins further protrudingthrough respective apertures in the first bus bar.
 2. The powerdistribution system of claim 1, wherein the first set and the second setof power supply pins are arranged in parallel fashion along a planeextending between the first side and the second side of the assembly. 3.The power distribution system of claim 2, wherein the first bus bar andthe second bus bar are of substantially identical cross-sectional sizeand are both disposed along a single row within a first portion of aninterior height of the power shelf assembly.
 4. The power distributionsystem of claim 3, wherein the first set and the second set of powersupply pins are configured for electrical coupling with one or morepower supply units positioned between the first bus bar and the secondside of the assembly.
 5. The power distribution system of claim 4,further comprising an insulating material disposed about an internalcircumference of the apertures in the first bus bar, wherein the secondset of one or more power supply pins is electrically insulated from thefirst bus bar.
 6. The power distribution system of claim 4, wherein thefirst portion of the height of the assembly comprises 50% or less of theheight of the power shelf assembly.
 7. The power distribution system ofclaim 6, wherein a second portion of the height of the assembly definesan air channel configured for cooling air passing through the assembly.8. The power distribution system of claim 7, further comprising aprinted circuit board mounted within the second portion of the height ofthe assembly, wherein a space between the bus bars and the printedcircuit board defines the air channel.
 9. The power distribution systemof claim 8, wherein the printed circuit board comprises one or moreelectrical communications signal interconnects between the one or morepower supply units and respective connectors disposed along an exteriorof the first side of the assembly.
 10. The power distribution system ofclaim 8, wherein the printed circuit board comprises one or more inputpower interconnects between the one or more power supply units andrespective connectors disposed along an exterior of the first side ofthe assembly.
 11. A power distribution system comprising: a power shelfassembly having a first side, an opposing second side, a definedinterior between the first and second sides, and one or more channelsfor receiving power supply units inserted via the second side, wherein afirst portion of an interior height of the assembly defines an airchannel for cooling air passing through the assembly; a first bus barextending across the defined interior and in parallel with a planecorresponding to the first side of the assembly; a second bus barextending across the defined interior and disposed in parallel betweenthe first bus bar and the first side of the assembly; a printed circuitboard mounted within the first portion of the height of the assembly,wherein a space between the bus bars and the printed circuit boarddefines the air channel, wherein the printed circuit board comprises oneor more electrical communications signal interconnects between the oneor more power supply units and respective connectors disposed along anexterior of the first side of the assembly; and a plurality of powersupply pins arranged in a single row and extending transverse to theplane corresponding to the first side of the assembly, the pinsconfigured for electrical coupling with the one or more inserted powersupply units, and for each of one or more groups of power supply pinscorresponding to a number of channels in the assembly, a first set ofone or more of the plurality of power supply pins extending from thefirst bus bar toward the second side of the assembly; and a second setof one or more of the plurality of power supply pins extending from thesecond bus bar toward the second side of the assembly.
 12. The powerdistribution system of claim 11, wherein the first and second bus barsare disposed within a second portion comprising 50% or less of theheight of the power shelf assembly.
 13. The power distribution system ofclaim 11, wherein the printed circuit board comprises one or more inputpower interconnects between the one or more power supply units andrespective connectors disposed along an exterior of the first side ofthe assembly.
 14. A power distribution system comprising: a power shelfassembly of one rack unit (1U) having a first side, an opposing secondside, third and fourth opposing sides extending between the first andsecond sides, and a top and a bottom defining a height; a first bus barextending between the third and fourth sides and in parallel with thebottom of the assembly, and residing within a first portion comprising50% or less of the height of the assembly; a second bus bar extending inparallel with the first bar and disposed within the first portion of theheight of the assembly, and between the first bus bar and the first sideof the assembly; a plurality of power supply pins arranged in a singlerow parallel with the bottom of the assembly, and extending transverseto a plane corresponding to the first side of the assembly, wherein oneor more of the plurality of power supply pins extends from the first busbar toward the second side of the assembly, and wherein each of aremaining one or more of the plurality of power supply pins extends fromthe second bus bar toward the second side of the assembly.
 15. The powerdistribution system of claim 14, further comprising a printed circuitboard mounted within a second portion of the height of the assembly,wherein a space between the bus bars and the printed circuit boarddefines an air channel for cooling air passing through the assembly.